mirror of
https://github.com/ipfs/kubo.git
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100 lines
3.5 KiB
Go
100 lines
3.5 KiB
Go
package corehttp
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import (
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"context"
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"fmt"
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"net/http"
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"time"
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blocks "github.com/ipfs/go-block-format"
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cid "github.com/ipfs/go-cid"
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coreiface "github.com/ipfs/interface-go-ipfs-core"
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ipath "github.com/ipfs/interface-go-ipfs-core/path"
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"github.com/ipfs/kubo/tracing"
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gocar "github.com/ipld/go-car"
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selectorparse "github.com/ipld/go-ipld-prime/traversal/selector/parse"
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"go.opentelemetry.io/otel/attribute"
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"go.opentelemetry.io/otel/trace"
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)
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// serveCAR returns a CAR stream for specific DAG+selector
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func (i *gatewayHandler) serveCAR(ctx context.Context, w http.ResponseWriter, r *http.Request, resolvedPath ipath.Resolved, contentPath ipath.Path, carVersion string, begin time.Time) {
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ctx, span := tracing.Span(ctx, "Gateway", "ServeCAR", trace.WithAttributes(attribute.String("path", resolvedPath.String())))
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defer span.End()
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ctx, cancel := context.WithCancel(ctx)
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defer cancel()
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switch carVersion {
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case "": // noop, client does not care about version
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case "1": // noop, we support this
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default:
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err := fmt.Errorf("only version=1 is supported")
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webError(w, "unsupported CAR version", err, http.StatusBadRequest)
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return
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}
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rootCid := resolvedPath.Cid()
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// Set Content-Disposition
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var name string
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if urlFilename := r.URL.Query().Get("filename"); urlFilename != "" {
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name = urlFilename
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} else {
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name = rootCid.String() + ".car"
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}
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setContentDispositionHeader(w, name, "attachment")
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// Set Cache-Control (same logic as for a regular files)
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addCacheControlHeaders(w, r, contentPath, rootCid)
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// Weak Etag W/ because we can't guarantee byte-for-byte identical
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// responses, but still want to benefit from HTTP Caching. Two CAR
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// responses for the same CID and selector will be logically equivalent,
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// but when CAR is streamed, then in theory, blocks may arrive from
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// datastore in non-deterministic order.
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etag := `W/` + getEtag(r, rootCid)
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w.Header().Set("Etag", etag)
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// Finish early if Etag match
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if r.Header.Get("If-None-Match") == etag {
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w.WriteHeader(http.StatusNotModified)
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return
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}
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// Make it clear we don't support range-requests over a car stream
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// Partial downloads and resumes should be handled using requests for
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// sub-DAGs and IPLD selectors: https://github.com/ipfs/go-ipfs/issues/8769
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w.Header().Set("Accept-Ranges", "none")
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w.Header().Set("Content-Type", "application/vnd.ipld.car; version=1")
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w.Header().Set("X-Content-Type-Options", "nosniff") // no funny business in the browsers :^)
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// Same go-car settings as dag.export command
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store := dagStore{dag: i.api.Dag(), ctx: ctx}
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// TODO: support selectors passed as request param: https://github.com/ipfs/kubo/issues/8769
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dag := gocar.Dag{Root: rootCid, Selector: selectorparse.CommonSelector_ExploreAllRecursively}
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car := gocar.NewSelectiveCar(ctx, store, []gocar.Dag{dag}, gocar.TraverseLinksOnlyOnce())
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if err := car.Write(w); err != nil {
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// We return error as a trailer, however it is not something browsers can access
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// (https://github.com/mdn/browser-compat-data/issues/14703)
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// Due to this, we suggest client always verify that
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// the received CAR stream response is matching requested DAG selector
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w.Header().Set("X-Stream-Error", err.Error())
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return
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}
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// Update metrics
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i.carStreamGetMetric.WithLabelValues(contentPath.Namespace()).Observe(time.Since(begin).Seconds())
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}
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// FIXME(@Jorropo): https://github.com/ipld/go-car/issues/315
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type dagStore struct {
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dag coreiface.APIDagService
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ctx context.Context
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}
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func (ds dagStore) Get(_ context.Context, c cid.Cid) (blocks.Block, error) {
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return ds.dag.Get(ds.ctx, c)
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}
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